Steam generator



Feb. 9, 1937. G. W ASAATHQFF 2,070,182

STEAM GENERATOR'V FiledJuly 25, 1935 2 Sheets-Sheet 1 i g x INVEN R GEOR E VV. SAATHOFF ATTORNEY K Feb. 9, 1937. G. w, SAATHOFF 2,070,182

STEAM GENERATOR Filed July 25l 1955 2 Sheets-Sheet 2 INVENTOR GEORGE W. SAAT HOFF Patented Feb. 9, 1937 STEAM GENERATOR George W. Saathoif, South Orange, N. J., assigner to Doherty Research Company, New York, N. Y., a corporation of Delaware Application July 25, 1935, Serial No. 33,025

3 Claims.

This invention relates to steam generating apparatus, and is more particularly concerned with improved steam generating apparatus adapted for use in supplying low pressure steam to domestic heating systems and the like.

A primary object of the present invention is to provide a steam generating unit which is economical to build and operate, and which can be safely operated by an unskilled operator. To accomplish this object one feature of the improved steam generating apparatus is that it embodies two separate and distinct boilers assembled in an integral unit in such a manner that steam is generated in a primary boiler by heat transferred through evaporation surfaces from a name or primary source of heat, and generation of steam in the secondary boiler is eifeoted by transfer of heat from the water and steam in the primary boiler. Only steam generated in the secondary boiler is withdrawn for use. The secondary boiler functions as a condenser within the steam zone of the primary boiler; so that the primary boiler may be operated as a closed unit from which no steam is 25 tapped and within which steam is continuously generated and then condensed. By this design all danger is eliminated of water becoming low on one side of an evaporating surface exposed to high temperature flame on the other, and the 30 unit needs no low water alarm apparatus, which is expensive to install and operate and is not very reliable in operation because of the number of moving parts and electrical elements usually attached thereto.

Another object of the invention is to provide a primary boiler of the type above referred to adapted for rapid generation of steam and also adapted for using fuel which does not require forced draft. With this object in View the pre- 40 ferred design of the primary boiler is that of a one-pass boiler having a large evaporation surface relative to its Water storage capacity, and also having a water storage section of annular cross-section surrounding a centrally located re chamber and combustion flue laid out on a substantially horizontal major axis. The evaporation surface of the boiler is greatly increased by mounting a plurality of water circulating tubes vertically (or at an angle of less than 45 from the vertical) as transverse baffles in the single pass combustion flue of the boiler-these tubes permitting small volumes of water to circulate very rapidly on the percolator principle.

With the above and other objects and features in View, the invention resides in the improved primary-secondary steam generator unit which is hereinafter described and particularly defined by the accompanying claims.

The invention will now be particularly described by reference to the design illustrated in the accompanying drawings, in Which:

Fig. 1 is a view in vertical side section, with parts shown in elevation, of a preferred embodiment of the invention, taken on the line l-I of Fig. 2.

Fig. 2 is a plan view in section, with parts in elevation, taken on the line 2-2 of Fig, l.

Fig. 3 is a view in vertical end section, taken on the line 3 3 of Fig. 1.

Fig. 4 illustrates diagrammatically how the secondary boiler may be connected in closed circuit with a steam jet evaporative cooler unit and with a steam condenser-water heater unit.

In the accompanying drawings, I0 indicates the cylindrical outer shell and I2 and i4 the end plates of a closed primary boiler it having a substantially constant water storage level it. A one-pass re chamber (20) and combustion nue 22 is disposed longitudinally within the water storage and evaporation zone of boiler i 6 so that evaporating plates 24, which form the base, top and side Walls of chamber 20 and iiue 22, are entirely surrounded by a body of water during normal operation of the boiler. The floor of re chamber 20 is protected by an insulating refractory lining 26. Also the side walls of chamber 20 are provided with refractory linings 28, and a row of vertically disposed water circulating tubes 30 is embedded in each wall lining 28. Additional rows of vertical water circulating tubes 30 in closely spaced staggered relation, are disposed as baiiles throughout the length of flue 22 and serve to greatly extend the heat transfer surface of the primary boiler. Water for lling the boiler to approximately the level iS may be introduced through a feed inlet 32. As shown in Fig. 3, boiler I6 is fitted with a water level gauge 34, a steam gauge 36, and a safety valve 38. The primary boiler I6 is strongly built to withstand operation as a Sealed unit under high pressure up to at least 100 lbs. per square inch. Heat for operating the boiler may be Supplied by a gas or oil burner 4i] mounted as shown at the inlet of iire chamber 20 and operated under either natural or forced draft. Automatic pressure or thermal control of the fuel supply to burner 40 is contemplated, although not illustrated.

As previously indicated, the apparatus includes a secondary boiler 42 assembled as an integral unit Within the upper steaming zone of primary boiler i6, so that the generation of low pressure steam in the boiler 42 is effected by heat transfer from the high pressure steam bath maintained in boiler I6. Boiler 42 embodies two combination water and steam boxes 44 and 45 mounted respectively on the upper outside portions of end plates I2 and I4. Boxes 44 and 45 are communicably connected by a number of staggered rows of horizontally disposed closely spaced evaporation tubes 48, as well as by a large steam equalizing pipe 50. Boiler 42 is provided with a water inlet 52, and with a Water glass 54 by which to observe the water level 56. A steam pressure gauge and automatic Water level -control is also contemplated for boiler 42 (not shown).

Steam generated in secondary boiler i2 is removed therefrom through pipes 58 and header 6i? to a place of use. Steam generated in primary boiler I6 is condensed within the boiler by contact with the evaporation tubes i8 of the secondary boiler. Under the preferred plan of operation, no steam is withdrawn from the boiler it, so that there is absolutely no chance of the water therein dropping to a dangerously low level. The condenser effect of the tubes t3 of the secondary boiler on the steam generated in primary boiler iii may be advantageously supplemented by disposing one or more Water heating tubes G2 (forming part of a hot water heating system) in the steam space of the boiler i6 and/or in the water or steam storage space of boiler d2.

As previously stated, the steam generator herein described is particularly adapted for use in supplying the heating requirements of domestic heating systems. However, an adaptation thereof has been illustrated in Fig. 4 which includes both indirect cooling and indirect heating. According to this plan steam generated in the secondary boiler l2 is withdrawn from header 63 through a pipe t@ by which the steam is conducted to and through a thermocompressor element 66 of a steam jet vacuum evaporator-cooler unit 6B. Water introduced by a spray fio into the unit 58 is evaporated under the high vacuum created in unit 68 by the action of element to, and this rapid evaporation cools a body of water circulating through coils 'i2 mounted Within unit 5S to a temperature of say 45 F. This cold water may then be circulated through a domestic air conditioning system during hot weather for cooling purposes.

After passing through the compressor S the steam from boiler 32, together with water vapor evaporated from cooler S8, is conducted to a condenser ifi, which may be operated as an air condenser or as a water circulation condenser. When operating condenser 'M as a Water circulation condenser, water which is circulated through coils l5 thereof may be heated sufiiciently by heat absorbed from the condensing steam so that it may be used as the source of hot water for a domestic hot Water heating system. The condenser lli is provided with an exhaust pipe iitted up with a Vacuum pump 'i6 to initiate operation thereof when the thermocompressor 6% first starts operation. Condensate which is collected by the operation of condenser lli is withdrawn by a pump 78, and measured amounts are returned by the pump respectively to the feed inlet 52 of boiler 42, and by a pipe Sii to water storage (not shown). Thus in the apparatus illustrated in Fig. 4 the steam from the boiler i2 follows a closed cycle until it is returned as condensate to the feed inlet 52. Water which is not evaporated in cooler 68 is recirculated by a pump 8?. to spray lo, and make up water is supplied to the spray through a pipe S4. During cold weather cooler S3 may be operated as a heater for heating water circulating through coils 12. This is accomplished by closing a valve 86 in the connection between thermocompressor 66 and condenser 14 and circulating steam introduced by the compressor 66 around the coils 12 in chamber 68. Coils 'l2 then function as a condenser for the steam, and the condensate which collects in the bottom of chamber 68 may be returned to feed pipe 52 of boiler 42 by pump 82 and a valved pipe 88.

Having thus described the invention, what is claimed as new is:

l. A primary-secondary steam generator unit comprising a combustion chamber and communicating combustion iiue, a primary boiler having its Water storage and evaporation chamber surrounding the combustion chamber and flue,

and a secondary water tube boiler having evaporation tubes and a steam equalizing drum mounted Within the upper part of the evaporation Zone and in the steam Zone of the primaryv boiler in position to receive heat from the water and steam in the primary boiler, the evaporation tubes and steam equalizing drum of the secondary boil-er constituting a condenser within the steam Zone of the primary boiler whereby the primary boiler functions as a self-contained closed circuit steam generator-condenser unit.

2. A primary-secondary steam generator unit adapted for supplying steam to a domestic heating system and comprising a primary re tube boiler in the form of a horizontal drum having a steam storage and condensing zone in its upper portion and a water storage and evaporation zone in its lower portion, a combustion chamber disposed longitudinaliy within the lower portion of the primary boiler, a plurality of water circulating tubes mounted as transverse baiiies within the combustion flue and arranged to increase the evaporation surface of the primary boiler, and a secondary Water tub-e boiler having evaporation tubes and a steam equalizing drum disposed longitudinally within the upper portion of the primary boiler in position to receive heat from the steam in the primary boiler and having water feed and steam withdrawal pipes communicably connected respectively with the evaporation tubes and with the steam equalizing drum, the evaporation tubes and steam equalizing driun of the secondary boiler constituting a condenser within the steam zone of the primary boiler whereby the primary boiler may function as a self-contained closed circuit steam generator-condenser unit While the secondary boiler serves as the source of steam supply for the heating system.

3. A primary-secondary steam generator unit comprising a combustion chamber and communicating combustion flue, a primary boiler having its water storage and evaporation chamber surrounding the combustion chamber and flue, a refractory lining for the combustion chamber Within which water circulating tubes are disposed With their ends communicably connecting the portions of the evaporation Zone above and below the combustion chamber, and a secondary water tube boiler having its evaporation tubes mounted within the upper part of the evaporation zone and in the steam zone of the primary boiler in position to receive heat from the water and steam in the primary boiler, the evaporation tubes of the secondary boiler constituting a condenser Within the steam zone of the primary boiler whereby the primary boiler functions as a self-contained closed circuit steam generator-condenser unit.

GEORGE W. SAATHOFF. 

